Support performance.now() in workers.

Source/modules/performance/WorkerPerformance.h

Index: Source/modules/performance/WorkerPerformance.h
diff --git a/Source/core/html/ime/Composition.h b/Source/modules/performance/WorkerPerformance.h
similarity index 76%
copy from Source/core/html/ime/Composition.h
copy to Source/modules/performance/WorkerPerformance.h
index 6562b5f75fd19cc8e80409327f7f8a5881bcf1df..86245992cc081e069ec1d717cce5b40b4ec4129f 100644
--- a/Source/core/html/ime/Composition.h
+++ b/Source/modules/performance/WorkerPerformance.h
@@ -28,34 +28,29 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef Composition_h
-#define Composition_h
+#ifndef WorkerPerformance_h
+#define WorkerPerformance_h
 
-#include "bindings/v8/ScriptWrappable.h"
+#include "core/dom/ContextDestructionObserver.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
 
 namespace WebCore {
 
-class Node;
-class Range;
+class ScriptExecutionContext;
 
-class Composition : public RefCounted<Composition>, public ScriptWrappable {
+class WorkerPerformance : public RefCounted<WorkerPerformance>, public ContextDestructionObserver {

[levin, 2013/06/13 19:55:22]

How does this use ContextDestructionObserver?

How is it deleted?

[abarth-chromium, 2013/06/13 20:18:19]

The pointer to the ScriptExecutionContext is stored in the
ContextDestructionObserver.  That means the pointer is zeroed out automatically
when the ScriptExecutionContext dies.
It's refcounted, which means it dies when the references from JavaScript and
from WorkerContextPerformance go away.

[levin, 2013/06/13 22:19:08]

ok.

Somehow I missed the usage of sec completely.... I feel like I missed a lot
here. But thanks for your patience in helping with the basics :).

 public:
-    static PassRefPtr<Composition> create(Node*, Range*);
-    ~Composition();
+    static PassRefPtr<WorkerPerformance> create(ScriptExecutionContext* context) { return adoptRef(new WorkerPerformance(context)); }
+    ~WorkerPerformance();
 
-    Node* text() const { return m_text.get(); }
-    Range* caret() const { return m_caret.get(); }
+    double now() const;
 
 private:
-    Composition(Node*, Range*);
-
-    RefPtr<Node> m_text;
-    RefPtr<Range> m_caret;
+    explicit WorkerPerformance(ScriptExecutionContext*);
 };
 
-} // namespace WebCore
+}
 
-#endif // Composition_h
+#endif // WorkerPerformance_h